Module Ocamlbuild_js_of_ocaml

Ocamlbuild plugin to build with js_of_ocaml


Initialize the js_of_ocaml ocamlbuild plugin with the following code in

let _ = Ocamlbuild_plugin.dispatch Ocamlbuild_js_of_ocaml.dispatcher

Side note: Ocamlbuild_plugin.dispatch should be used only once. The last call will override previous ones.

With Oasis

If you use oasis, should look like:

let _ =
    (fun hook ->
       dispatch_default hook;


Build a JavaScript program myprog.js by calling the command:

ocamlbuild -use-ocamlfind -plugin-tag "package(js_of_ocaml.ocamlbuild)" myprog.js

It will first build the bytecode myprog.byte and finally produce myprog.js (in _build).


One can pass option to the Js_of_ocaml compiler using tags. See <<a_manual chapter="options" |Options>>.

Available tags:

  • pretty: Pretty print the generated javascript.
  • debuginfo: Output debug information.
  • noinline: Disable inlining
  • sourcemap: Generate sourcemap
  • tailcall(none): Set the tailcall optimisation (default "trampoline")
  • opt(3): Set the compilation profile (default 1)
  • debug: enables pretty, debuginfo, sourcemap


In the _tags file:

<myprog.js>:pretty, opt(3)


val dispatcher : ?⁠oasis_executables:Ocamlbuild_plugin.Pathname.t list -> Ocamlbuild_plugin.hook -> unit

The main dispatcher

?oasis_executables is the paths of the executables (having the .byte extension) you want to compile as a javascript executable. The former executables are still compiled.

Side note: Ocamlbuild_plugin.dispatch should be used only once as it record only one function for an ocamlbuild module.

Low level functions

val oasis_support : executables:Ocamlbuild_plugin.Pathname.t list -> unit

Map each targets given as argument to ocamlbuild and replace each element that exists in ~executables by its corresponding .js target.